This invention relates to a semiconductor component. In particular, this invention relates to a semiconductor component comprising an insulated gate field effect device and a protection device for regulating the current through the insulated gate field effect device so as, for example, to reduce the possibility of parasitic thyristor action, that is so-called latch-up, which could result in the ultimate destruction of the insulated gate field effect device.
EP-A-392530 discloses a drive circuit for an insulated gate field effect bipolar transistor (IGBT) in which a current sensor of unspecified type senses the current through the IGBT and provides an overcurrent signal to a control system, again of unspecified type, which acts to operate switches to reduce the gate drive voltage of the IGBT. As described in EP-A-392530, a zener diode is connected in a path between the main electrodes (normally known as the anode and cathode electrodes but referred to in EP-A-392530 as the collector and emitter electrodes) of the IGBT to restrict the current flow through the IGBT by providing a reactive current path. The zener diode is connected to the gate of an insulated gate field effect transistor (IGFET or MOS) which is turned on when the reactive current becomes sufficiently high to divert part of the supply current, thereby reducing the gate drive voltage applied to the IGBT.
The drive circuit described in EP-A-392530 is relatively complicated and requires external elements such as the control system and current sensor to operate. In addition, as the operation of the switches used to regulate the gate drive voltage is controlled via the external control system, the current regulation function of the drive circuit may function quite slowly.
It is an aim of the present invention to provide a semiconductor component which comprises an insulated gate field effect device, such as an IGBT, together with an integral protection device.